It has become well established that there are major public health benefits from regular endoscopic examinations of a patient's internal structures, such as the alimentary canals and airways, e.g., the colon, esophagus, stomach, lungs, uterus, urethra, kidneys, and other internal organ systems. Conventional imaging endoscopes used for such procedures generally comprise a flexible tube with a fiber optic light guide that directs illuminating light from an external light source to the distal tip where it exits the endoscope and illuminates a region to be examined. An objective lens and fiber optic imaging light guide communicating with a camera at the proximal end of the scope, or an imaging camera chip at the distal tip, produce an image that is displayed to the examiner. In addition, most endoscopes include one or more working channels through which medical devices, such as biopsy forceps, snares, fulguration probes, and other tools may be passed.
Conventional endoscopes are expensive hand-assembled medical devices costing in the range of $25,000 for an endoscope, and much more with the associated operator console. Because of the expense, these endoscopes are built to withstand repeated disinfections and use upon many patients. Conventional endoscopes are generally built of strong composite materials, which decrease the flexibility of the endoscope and thus can compromise patient comfort. Furthermore, conventional endoscopes are complex and fragile instruments that frequently need expensive repair as a result of damage during use or during a disinfection procedure.
Low cost, disposable medical devices designated for a single use have become popular for instruments that are difficult to sterilize or clean properly. Single-use, disposable devices are packaged in sterile wrappers to avoid the risk of pathogenic cross-contamination of diseases such as HIV, hepatitis, and other pathogens. Hospitals generally welcome the convenience of single-use disposable products because they no longer have to be concerned with product age, overuse, breakage, malfunction, and sterilization. One medical device that has not previously been inexpensive enough to be considered truly disposable is the endoscope, including, for example, a colonoscope, ureteroscope, gastroscope, bronchoscope, duodenoscope, etc. Such a low cost endoscope is described in U.S. patent application Ser. No. 10/406,149, filed Apr. 1, 2003, and in a U.S. Continuation-in-Part application Ser. No. 10/811,781, filed Mar. 29, 2004, and in a U.S. Continuation-in-Part patent application Ser. No. 10/956,007, filed Sep. 30, 2004, that are assigned to Scimed Life Systems, Inc., now Boston Scientific Scimed, Inc and are herein incorporated by reference.
The endoscope disclosed in U.S. patent application Ser. No. 10/406,149, U.S. patent application Ser. No. 10/811,781 and in U.S. patent application Ser. No. 10/956,007 contains a CMOS image sensor capable of producing digital image signals. Depending on the version of the sensor, the digitized image data may be transmitted from the distal tip of the endoscope in a serial or parallel format. The use of a digital video format enhances image quality by eliminating the introduction of noise during the transmission of the signal along the length of the endoscope. The analog-to-digital conversion is integral to the image sensor itself, further mitigating the opportunity for noise to be introduced into the image. Although the use of a digital image sensor produces better quality signals, there are some instances where it is desirable to use such a device with an existing analog video console. Therefore, there is a need for an imaging adapter and method for signal conversion that allows a medical imaging device having digital video output to be used with a system having conventional analog video input. Such an imaging adapter and method would allow a broader mass market to benefit from the advantages of using digital imaging in a low cost disposable endoscope.